The invention relates generally to milking plants. More particularly, the invention relates to cleansing arrangements for milking machines.
Milking machines have pipes through which milk from the cows flows to receptacles. These pipes and receptacles must be cleansed periodically.
A known cleansing arrangement for milking machines has a storage vessel for a concentrated cleansing fluid. The storage vessel is connected to a metering device via a cleansing fluid supply pipe. The metering device is located at the upper end of a reservoir for the cleansing fluid and has an outflow opening at its lower end to permit the cleansing fluid to flow into the reservoir. The outflow opening is regulated by a vacuum-actuated valve member which causes the outflow opening to be closed in response to the creation of a vacuum in the metering device. The metering device has a throttling opening which communicates with the atmosphere or with the interior of the reservoir and causes the vacuum within the metering device to be destroyed when suction is no longer applied to the metering device.
A vacuum line which directs the cleansing fluid through the pipes and receptacles of the milking machine communicates with the reservoir. The vacuum line has an inlet end which is connected with the lower end of the reservoir and an outlet end which is connected with the upper end of the reservoir. A vacuum is created in the vacuum line whenever the milking machine is to be cleansed.
A source of water for diluting the cleansing fluid is connected with the metering device by means of a water supply pipe. The water supply pipe has a branch which connects with the vacuum line near the inlet end of the latter thereby establishing communication between the vacuum line and the metering device. This makes it possible to generate a vacuum in the metering device and thus draw cleansing fluid from the cleansing fluid storage vessel into the metering device by suction. The water supply pipe has an outlet opening at the upper end of the metering device and a floating valve member inside the metering device causes this outlet opening to be closed when the cleansing fluid in the metering device reaches a predetermined level. This causes the suction in the metering device to be terminated and stops the flow of cleansing fluid into the metering device. A valve is provided in the water supply pipe to isolate the metering device from the vacuum line.
A cleansing arrangement of the type outlined above is known from German Auslegeschrift No. 26 08 585. Here, the metering device has a cover which is provided with a connection for the cleansing fluid supply pipe. In order to satisfactorily cleanse the vacuum line and the parts of the milking machine connected therewith, the cleansing procedure is performed with an acidic cleansing fluid or an alkaline cleansing fluid. When a switch in the cleansing fluid is to be made, the connection on the cover of the metering device must be connected with a different supply pipe leading to a source of the new cleansing fluid. Since residues of the previous cleansing fluid remain in the connection, crystalline deposits are formed when the new cleansing fluid, which has a different consistency and chemical composition than the previous cleansing fluid, is sucked into the connection. These deposits reduce the flow cross-section of the connection and may even constrict the same entirely, especially since the connection extends upwards from the cover of the metering device and cannot be reached by water which is admitted into the metering device for cleansing of the same.